Process for the preparation of N-[2-[4-(aminosulfonyl) phenyl]ethyl]5-methylpyrazinecarboxamide

Abstract

A process for the preparation of N-[2-[4-(amino-sulfonyl)phenyl]ethyl]-5-methylpyrazinecarboxamide is described which is simple and effective.

What is claimed is: 
     
       1. A process for the preparation of N-[2-[4-(aminosulfonyl)phenyl]ethyl]-5-methylpyrazine-carboxamide of the formula I: ##STR21## consisting of: i) treating 5-methylpyrazine-2-carboxylic acid of the formula VIII: ##STR22##  with methanol under reflux to obtain 5-methylpyrazine-2-carboxylic acid methyl ester of the formula VIII A: ##STR23## ii) reacting 5-methylpyrazine-2-carboxylic acid methyl ester of the formula VIII A with 2-phenylethylamine of the formula II: ##STR24##  at 100° to 200° C. to obtain 5-methylpyrazine 2-(2-phenylethyl) carboxamide of the formula IX: ##STR25## iii) chlorosulfonating the 5-methylpyrazine-2-(2-phenylethyl)carboxamide of the formula IX with chlorosulfonic acid at 0°-45° C. to obtain [N-[2-[4-(chlorosulfonyl)phenyl]ethyl]-5-methylpyrazine carboxamide] of the formula X: ##STR26## iv) and treating the [N-[2-[4-(chlorosulfonyl)phenyl]ethyl]-5-methyl purazinecarboxamide] of the formula X with ammonia to obtain N-[2-[4-(aminosulfonyl)phenyl]ethyl]-5-methylpyrazine carboxamide of the formula I. 
     
     
       2. A process as claimed in claim 1, wherein the reaction of compounds of the formulae VIII A and II is carried out at 120°-150° C. 
     
     
       3. A process as claimed in claim 1, wherein the compound of the formula IX is chlorosulfonated with chlorosulfonic acid at 5°-40° C. 
     
     
       4. A process as claimed in claim 2, wherein the compound of the formula IX is chlorosulfonated with chlorosulfonic acid at 5°-40° C. 
     
     
       5. A process as claimed in claim 1, wherein crude 5-methylpyrazine-2-carboxylic acid is treated with methanol in step (i). 
     
     
       6. A process as claimed in claim 2, wherein crude 5-methylpyrazine-2-carboxylic acid is treated with methanol in step (i). 
     
     
       7. A process as claimed in claim 3, wherein crude 5-methylpyrazine-2-carboxylic acid is treated with methanol in step (i).